Mower type: Scotts by John Deere - L1742 - 42" / 17 hp

Issue: Blades stop when deck is lowered to 3. They do spin (lightly) at levels 4 and 5... but, it doesn't seem like the blades are running 'full' power.

Actions to try and fix: Belt has been replaced.

Notes: Deck is clean. Throttle is engaged enough to spin blades. We know its not the belt.
The machine is clean. The blades just don't seem to be spinning as they should. When it was working at full strength, it would bog down the mower slightly when the blades were engaged. Now you can barely tell the blades are engaged... the only reason I know they are spinning is because grass is shooting out.

Question(s):
*What device is responsible for spinning the blades at full strength?
*Is there something specific that needs to be adjusted/replaced?
*Any other ideas?

Thank You! -JROWSCOTTS

Check your PTO cable .make sure its moving the pulley arm in and out when engaged.
Where the cable comes in to the deck , that bracket has slots in it see if you can move it some.
Luck